Abstract : This document updates Shell's December 19, 1983, Risk Assessment for 1,2-dibromo-3-chloropropane (DBCP). The health-related data on DBCP are reviewed both from experimental animals and from human studies. A number of new animal studies have been published during the past three years and the results of a substantial epidemiology study are available. The new information reinforces Shell's earlier conclusion that realistic partial lifetime exposure to concentrations of DBCP below 100 ppb in drinking water poses no significant risk of an adverse health effect. Indeed, the very existence of risks to humans who might be exposed to drinking water at these levels is speculative. This summary document describes the process used to arrive at our conclusion. More details are provided in the attached appendices and copies of some unpublished reports are included.